Linksys AG241 Hermeified

[Fizzycapola]

Original Specification:
7 x Hermei 470uF 16V
4 x Hermei 33uF 16V
3 x Hermei 1000uF 16V
2 x G Luxon 10uF 16V

Full replacement I used:
1 x Rubycon ZLH 470uF 50V
6 x Panasonic FM 470uF 25V (note: any taller caps will not fit in case)
(note2: the far right of these (front to view) do not trim lead too much as cap needs movement to fit in casing)
3 x Panasonic FM 1000uF 16V
2 x Sanyo Oscon SP 15uF

Common faulty part: 33uF Hermei illustrated in picture. Resulting in "connected/disconnected/connected..." showing up on connected computers.

Workarounds: Force connection at 10M instead of auto. Replace 33uF Hermei with any good capacitor. I used a fresh 2.2uF Panasonic ECA 100v for testing and it seemed great, I then inserted a Rubycon 56uF later. Problem never re-appeared of hinted to re-appear.

In the blue box I show what I feel is an important capacitor relating to how your internet behaves. Changing this for me was of great interest. I tried many different capacitor types here. I found Panasonic FM 16V 2200uF fitted nicely on it's side here made the internet feel smooth and fast. Also I used surface mount Oscon connected to Panasonic FM 470uF connected to WIMA 1uF, the internet felt extremely responsive (pages appeared instead of loaded /connected) with this particular combination of all 3 connected into the socket. A side effect of these combinations seemed to be more frequent PPOA authentication drops. After thorough testing, for conformity and stability a single fresh PFM470uF was inserted to comply with original specs.

What wasn't fixed:
Noise, it wasn't possible to fix the noise issue. Changing the voltage of the PSU appeared to change the tone of the noise. Minimum voltage the modem operated for me was 7.5 volts. Perhaps it was most stable receiving 9v. Note: The supplied PSU reported 17v on my multimeter.
PPoA Authentication Drop outs. (Particularly the first hour of usage.)
Decreasing reported connection speed over time.
Necessity to reboot the device occasionally for optimal performance.

Quick summary:
Replace 33uF Hermei to fix LAN connection issue.

Use self adhesive RAMSINKS on hot parts. But don't overdo it, the router appears to like a bit of heat to work stable.

Cut side vents using mesh and edging for cooling and asthetics if you want.

Changing the capacitor illustrated by the blue box appears to affect internet the most. But the real problem of the device appears to lay elswhere from just the electrolytic capacitors alone.

Special Note: The more cooling I put on the CPU the more PPoA drop outs would occur. So I removed the messy copper heatsink system altogether and replaced with a single Aluminium RAMsink on the core. (doubling to 2 of these resulted in frequent PPoA dropouts for some reason) With this minimal heatsinking and the all good capacitors, was able to run for a week without noticing drop outs, also download speeds were faster than with Hermei. I achieved highest ever up/down speeds with this configuration. I miss the responsive feel of when I used 3 caps in the blue box illustration, but I guess you can't have everything.

[zandrax]

Re: Linksys AG241 Hermeified

Special Note: The more cooling I put on the CPU the more PPoA drop outs would occur. So I removed the messy copper heatsink system altogether and replaced with a single Aluminium RAMsink on the core. (doubling to 2 of these resulted in frequent PPoA dropouts for some reason) With this minimal heatsinking and the all good capacitors, was able to run for a week without noticing drop outs, also download speeds were faster than with Hermei. I achieved highest ever up/down speeds with this configuration. I miss the responsive feel of when I used 3 caps in the blue box illustration, but I guess you can't have everything.

Good work Fizzy.
I can't really understand why excessive coling makes everything more unstable, but I agree with your choices: stability is more important than performance.

Zandrax

[Fizzycapola]

Re: Linksys AG241 Hermeified

Heres the connection readings through different stages.

[zandrax]

Re: Linksys AG241 Hermeified

@ Fizzy: your line is very bad (excessive line attenuations) and you're quite far from you Adsl exchange box ([noise] margins too low), so it's a surprise your router doesn't hang every few hours: stick with Adsl1, don't change to Adsl2 unless you want to lose your connection. As a comparison, my line is about 1 mile (1.5 km) from nearest exchange box and values are barely enough for handling a full Adsl1 bandwith:

Link ADSL Downstream Upstream Connection bandwith
8128 kbps 480 kbps Line attenuation
16 db 5 db Noise margin
12 db 21 db
Note that margins are traffic-dependant: at night there's fewer noise in telephone lines so you should expect a slightly greater value that at noon (say a 1-2 dB difference). My downstream margin ranges from 12 to 13 dB.

So the cap combo I'd choose are those allowing the bigger margins available: the Panasonic FM - Nichicon HD combo or the PFM - Sanyo & Ruby one.

Zandrax

P.S.: don't stare at my download bandwith: they're useless [I managed to saturate 8 Mb only once, it was a big download from a fast server] unless you can upload more.